Korg EA-1

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The EA1 contains two independent programmable monosynths, with independent mono outputs and effects, while the {ln:Korg ER-1 mk II 'ER1 rhythm synth} is a 6-voice stereo beatbox offering two sample-based voices and four physically modelled ones. Both provide built-in pattern-based sequencing along with plentiful helpings of real-time control, including a Motion Sequencer which allows (some of) your real-time knob movements to be recorded within a song.

Analogue Model

In terms of sound generation, the EA1 contains two independent programmable monophonic synthesizers, each of a straightforward two-oscillator design and combining traditional analogue features such as portamento, oscillator sync, and ring modulation with more unusual features like Decimation (bit reduction) and distortion. The full parameter list for each of the EA1's synths is as follows:


  • Osc 1 waveforms: Saw, Pulse, Triangle, External Audio.
  • Osc 2 waveforms: Saw, Pulse, Triangle.
  • Osc 2 Pitch Offset (variable over four octaves).
  • Osc Mod: Ring Mod, Sync, Decimator.
  • Osc balance (between 1 & 2).
  • Portamento.


  • Cutoff.
  • Resonance.
  • EG Density.
  • Decay.


  • Level.
  • Distortion.


  • Type (Chorus/Flanger, Delay).
  • Depth
  • Time (controls chorus/flanger speed)

The synths in the EA1 are based around the analogue modelling technology used in Korg's Z1, and in this incarnation are laid out in a standard VCO-VCF-VCA-EG configuration. As you can see from the features list above, they offer a reasonable arsenal of controls and parameters to play with. The frequency range of the oscillators is wide, though Osc 1's isn't as great as that of Osc 2. Strangely, in their raw state the waveforms all sound vaguely samey: the ring modulator and sync settings, on the other hand, sound as you would expect from an analogue synth, and the Decimator imposes a down-sampled, grungy edginess to the waveform.

The filter is a good approximation of an analogue low-pass type that sounds more 'Japanese' than 'American' (or more Korg/Roland than ARP/Moog). Although it can be persuaded to self-oscillate, when doing so it displays some uneven peaks and troughs while sweeping. But, all told, not a bad filter.

korg_ea1_2The envelope control is a bit of a let-down, though. The Amp section isn't envelope-controllable at all -- it's either on or off -- and the filter control is severely limited, offering just an EG Int knob (envelope depth) with a centre null/off position and negative control to the left and positive to the right. This is coupled with a simple Decay control, and although there's no attack control one can be approximated using negative depth values with longer decay settings. Because there is no Amp envelope control, however, there is always a slight blip at the front of the sound.

The EA1's distortion is another on/off effect and works well enough, though it could hardly be described as subtle. There are, however, some redeeming features in the rest of the effects section. The Chorus/Flanger effect is basic, with only two controls, but sounds fine. The Depth parameter both controls the depth of the effect and introduces feedback at the higher settings, while the Time control (or speed in this case) ranges from the very slow to the ridiculously fast (0.2Hz-5kHz) -- which is actually fast enough produce audio-frequency (and hence audible) oscillation. As you can imagine, at the higher speeds this produces some beautifully crazed and over-the-top manipulations.

The other principal effect is Tempo Delay. Again, Depth controls two parameters (delay depth and feedback); with the Time knob set to minimum, the effect is like a flanger, while its maximum setting produces delays of a second or more. As the delay is synchronised to the pattern tempo the delay times will vary in accordance with the pattern speed, so at high tempos the maximum delay available will be shorter than at slower speeds. It's worth noting that because each synth has its own effects section some wonderfully syncopated bouncing echoes can be programmed.

Gripe Water

One gripe I have with many of the synth controls (and this also applies to the effects) is the sensitivity and stability of the knobs. The Osc 2 Pitch Offset is very sensitive, which admittedly makes sweeping the oscillator over four octaves very fast, but also makes it very difficult to fine-tune. The centre detent stop position rarely settles on the same tuning, sometimes locking on but sometimes gently drifting. The same applies to the Effect Time control: although it was great fun to almost randomly warble the sound at the slightest touch, sometimes I just wanted to set a particular delay time with no hassle.

Something which helps to alleviate this pet peeve of mine, though, is a useful feature called Original Value. This is just a single LED that glows whenever a control you are editing settles on its previously programmed value, which is useful if you are trying to go back a few editing stages without actually reloading a whole sound. Original Value works on all the knobs until you save the current settings to memory.

All synth settings are saved as a pair (Part 1&2) within an associated pattern: the pattern doesn't have to contain any sequenced notes, but all patterns will contain synth setting information and Parts can be freely copied and exchanged with other Patterns.

Vintage Model

It may not be a Minimoog or SH101, but the EA1 can still hold its own in company. Including not only two oscillators per synth but two synths, and some interesting modulation options into the bargain, is pure genius and makes up for some of the EA1's shortcomings. Coupled with the effects, the overall combination is very versatile and quite powerful. This is shown in some of the presets, which include some wonderfully deep and powerful bass lines and all manner of weird, wonderful and wacky synth tones and patterns. Hand on heart I couldn't say the EA1 is absolutely 'vintage', but it's definitely close to the cutting edge.

Horror of horrors, though, there's no LFO modulation for the oscillators, not even over MIDI -- maybe that's to come in the EA1 Mk2...

Pattern Sequencing

The 16 illuminated rubber buttons along the front are used for playing the synth voices (when this mode is activated using the Keyboard button) and also for editing, selecting, moving and deleting Parts, Patterns, Events and Songs. There are also two Transpose buttons that allow you to transpose individual notes across six octaves.

Patterns can be as short as 12 steps or as long as 64, and can be in 4/4, 3/4 or triplet timing. In Step Edit mode there are options for adjusting note Pitch and Gate times and inserting Rests and Ties, though there's no option for velocity control. When the sequencer is running the 16 keyboard buttons light up to show which notes in the selected Part are playing, providing a useful guide when editing individual notes within a pattern.

The sequencer section defaults to real-time loop recording mode and is easy to use in the extreme. Pressing the Record button (the large one on the left-hand side) makes it glows red, puts everything into record standby mode, and sets the Play/Pause button flashing green. Press the Play/Pause button and real-time looped recording begins. You now play your notes using the keyboard buttons (or external MIDI keyboard).

As you play, you can switch back and forth between the two synths, hold down the erase button and relevant note to delete bum notes and mistakes, and even engage the Motion Sequence feature and record a ittle knob-twiddling at the same time. The Motion Sequencer is an adaptation of a feature I first came across in Boss's DR202 Dr. Groove drum machine, and in the Dr. Groove you could record most of the knob movements within a pattern. With the EA1, however, you can only record a single knob or button activity for each synth voice. Once you've recorded your knob movements there are two playback options: Smooth plays back pretty much what you recorded, while TrigHold quantises the motion to the nearest 16th beat.


korg_ea1_3Song construction is also a straightforward affair. There are two input options: Step programming and Event programming. Step mode is just a matter of assembling a song by selecting the appropriate pattern at each step until you have assembled your complete song. Once you've assembled a Song there are editing options for Inserting, Deleting and Transposing Patterns.

Alternatively, Event mode is supposed to allow real-time recording of the Keyboard buttons into a song, but the results aren't very rewarding. There is a small warning in the instruction manual that states: "After rewinding a song it may not be possible to play back exactly according to the event data." You're not kidding, mate! It sounds rubbish, and it wasn't my style of playing either. My advice is to stick with the default Step mode.

A Suitable Case For Treatment

A feature that fell out of favour for years but is now being introduced on many new synths is an external audio input, and it was a pleasant surprise to find one included on the EA1. The external source needs to be at line level to get the best use of this feature, and once inside the EA1 the sound can be treated just like the oscillator waveforms. The Ring Modulator, Decimator, Distortion, Filter and Effects are all available for treating the external sound. Not only that but you can set up entirely different sets of treatments for each part, simultaneously.

Master & Slave

The EA1 has a reasonable MIDI specification, and external MIDI control is available for most of the EA1's parameters including saving and loading patterns and songs, MIDI sync (master or slave), selecting patterns and songs remotely, and individual MIDI keyboard or sequencer control of the synths. The EA1 will respond to pitch-bend data but it won't recognise velocity or modulation. Real-time parameter tweaks can be transmitted over MIDI as NRPNs, and edited in a sequencer such as Cubase, though as with the built-in Motion Sequencer only one parameter can be recorded for each synth. A nice touch is that the Keyboard buttons light up in response to incoming MIDI notes.

Other features are the familiar Tap Tempo, which is no worse (or particularly better) than most other beatbox versions I've tried, and Pattern Set. The latter is useful in that it allows you to assign 16 of your favourite patterns/synths to the 16 Keyboard buttons for instant access, and is a great feature for jamming or live playing.

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